This invention relates generally to optical equipment and more particularly concerns apparata for projecting a lens blank on a lens blocker.
In Pat. No 5,283,980, a lens blocker was disclosed for use in applying a block on a lens blank in preparation for mounting on a edgar. In using this and other types of lens blockers, it is sometimes desirable to project an image of a low power add of a multi-focal segmented lens on the LCD alignment screen target. It is further sometimes desirable to project or reflect the lay-out markings of a progressive lens as an image on the LCD alignment screen target. Similarly, projection of invisible or blended bifocals may also be desirable.
Most presently known lens projecting devices using LCDs accomplish the projection of low power adds, progressives and bifocals by use of a back light. In a back light arrangement, a lamp beneath the work surface illuminates a lens disposed between the work surface and the light source. Casting the image on the LCD surface with the work area above and the lens below has several draw backs. Since the LCD must be transparent, a unique LCD is required. Manipulation and alignment of the lens becomes difficult because manipulation occurs below the work surface while viewing occurs above the work surface and because the components of the blocker apparatus limit the hand movements of the operator. Moreover, the blocker apparatus so constricts space in the area where the lens must be placed that it is physically impossible to insert, much less manipulate, thicker lenses. One known projecting device deals with the above mentioned orientation problems by placing the lens above the work surface rather than beneath it but this imposes limitations on the viewing of low power multi-focal segments. In an attempt to overcome these limitations, edge lighting is used, but is ineffective in highlighting the multi-focal segments. Furthermore, edge lighting cannot be used to project the image of a dark lens or markings thereon.
It is, therefore, an object of this invention to provide a lens projecting device which projects an accurately defined image on an LCD surface. It is a further object of this invention to provide a lens projecting device which projects an image on an LCD work surface which is accurate when observed from any position above the LCD surface. It is another object of this invention to provide a lens projecting device which permits manipulation of the lens above the work surface of a lens blocking device. Another object of this invention is to provide a lens projecting device which can be used with a standard LCD. It is also an object of this invention to provide a lens projecting device usable with lenses of any thickness.